全文获取类型
收费全文 | 6513篇 |
免费 | 228篇 |
国内免费 | 25篇 |
专业分类
化学 | 4706篇 |
晶体学 | 50篇 |
力学 | 122篇 |
数学 | 801篇 |
物理学 | 1087篇 |
出版年
2023年 | 35篇 |
2022年 | 30篇 |
2021年 | 110篇 |
2020年 | 110篇 |
2019年 | 105篇 |
2018年 | 83篇 |
2017年 | 94篇 |
2016年 | 228篇 |
2015年 | 144篇 |
2014年 | 175篇 |
2013年 | 403篇 |
2012年 | 469篇 |
2011年 | 554篇 |
2010年 | 288篇 |
2009年 | 236篇 |
2008年 | 475篇 |
2007年 | 445篇 |
2006年 | 404篇 |
2005年 | 430篇 |
2004年 | 311篇 |
2003年 | 257篇 |
2002年 | 200篇 |
2001年 | 73篇 |
2000年 | 82篇 |
1999年 | 52篇 |
1998年 | 62篇 |
1997年 | 43篇 |
1996年 | 93篇 |
1995年 | 52篇 |
1994年 | 48篇 |
1993年 | 63篇 |
1992年 | 43篇 |
1991年 | 46篇 |
1990年 | 63篇 |
1989年 | 49篇 |
1988年 | 49篇 |
1987年 | 50篇 |
1986年 | 34篇 |
1985年 | 43篇 |
1984年 | 35篇 |
1983年 | 17篇 |
1982年 | 31篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 14篇 |
1975年 | 8篇 |
1974年 | 12篇 |
1973年 | 9篇 |
排序方式: 共有6766条查询结果,搜索用时 15 毫秒
1.
Russian Physics Journal - Aiming at problems of low probability of interception and poor anti-jamming performance of the multi-output radar, the numerical simulation based on a chaos optimization... 相似文献
2.
Ribeiro Sabrina Dias Meneguin Andria Bagliotti Barud Hernane da Silva Silva Jhonatan Miguel Oliveira Rafael L. Asuno Rosana Maria Nascimento de Tormin Thiago Faria Muoz Rodrigo Alejandro Abarza Filho Guimes Rodrigues Ribeiro Clovis Augusto 《Journal of Thermal Analysis and Calorimetry》2022,147(13):7265-7275
Journal of Thermal Analysis and Calorimetry - Cellophane film production generates cellulosic residues from scraps, edges, and low-quality films. In this work, cellophane was used as a raw material... 相似文献
3.
Svetlakova A. V. Mendez M. Sanchez Tuchin E. S. Khodan A. N. Traore M. Azouani R. Kanaev A. Tuchin V. V. 《Optics and Spectroscopy》2021,129(8):846-850
Optics and Spectroscopy - We study the photocatalytic activity of nanocomposites based on θ-phase alumina (Al2O3) with different TiO2 concentrations for heterogeneous photocatalysis and... 相似文献
4.
5.
An automorphism of an abelian variety induces a decomposition of the variety up to isogeny. There are two such results, namely the isotypical decomposition and Roan’s decomposition theorem. We show that they are essentially the same. Moreover, we generalize in a sense this result to abelian varieties with action of an arbitrary finite abelian group. An early version of this article was inadvertently published before all the revisions had been completed and then retracted [https://doi.org/10.1007/s00013-018-1244-3]. This article is the final peer reviewed version.
相似文献6.
AbstractWe study the inverse problem of parameter identification in noncoercive variational problems that commonly appear in applied models. We examine the differentiability of the set-valued parameter-to-solution map using the first-order and the second-order contingent derivatives. We explore the inverse problem using the output least-squares and the modified output least-squares objectives. By regularizing the noncoercive variational problem, we obtain a single-valued regularized parameter-to-solution map and investigate its smoothness and boundedness. We also consider optimization problems using the output least-squares and the modified output least-squares objectives for the regularized variational problem. We give a complete convergence analysis showing that for the output least-squares and the modified output least-squares, the regularized minimization problems approximate the original optimization problems suitably. We also provide the first-order and the second-order adjoint method for the computation of the first-order and the second-order derivatives of the output least-squares objective. We provide discrete formulas for the gradient and the Hessian calculation and present numerical results. 相似文献
7.
Yorioka introduced a class of ideals (parametrized by reals) on the Cantor space to prove that the relation between the size of the continuum and the cofinality of the strong measure zero ideal on the real line cannot be decided in . We construct a matrix iteration of c.c.c. posets to force that, for many ideals in that class, their associated cardinal invariants (i.e., additivity, covering, uniformity and cofinality) are pairwise different. In addition, we show that, consistently, the additivity and cofinality of Yorioka ideals does not coincide with the additivity and cofinality (respectively) of the ideal of Lebesgue measure zero subsets of the real line. 相似文献
8.
Y. T. Angel Wong Vinicius Martins Dr. Bryan E. G. Lucier Prof. Dr. Yining Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):1848-1853
Metal–organic frameworks (MOFs) have shown great potential in gas separation and storage, and the design of MOFs for these purposes is an on-going field of research. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a valuable technique for characterizing these functional materials. It can provide a wide range of structural and motional insights that are complementary to and/or difficult to access with alternative methods. In this Concept article, the recent advances made in SSNMR investigations of small gas molecules (i.e., carbon dioxide, carbon monoxide, hydrogen gas and light hydrocarbons) adsorbed in MOFs are discussed. These studies demonstrate the breadth of information that can be obtained by SSNMR spectroscopy, such as the number and location of guest adsorption sites, host–guest binding strengths and guest mobility. The knowledge acquired from these experiments yields a powerful tool for progress in MOF development. 相似文献
9.
Prof. Miguel A. Sierra Prof. Luis Casarrubios Dr. María C. de la Torre 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7232-7242
Overuse and misuse of antibacterial drugs has resulted in bacteria resistance and in an increase in mortality rates due to bacterial infections. Therefore, there is an imperative necessity of new antibacterial drugs. Bio-organometallic derivatives of antibacterial agents offer an opportunity to discover new active antibacterial drugs. These compounds are well-characterized products and, in several examples, their antibacterial activities have been studied. Both inhibition of the antibacterial activity and strong increase in the antibiotic activity of the parent drug have been found. The synthesis of the main classes of bio-organometallic derivatives of these drugs, as well as examples of the use of structure–activity relation (SAR) studies to increase the activity and to understand the mode of action of bio-organometallic antimicrobial peptides (BOAMPs) and platensimicyn bio-organometallic mimics is presented in this article. 相似文献
10.